A major study has found that fumes emitted from vehicle exhausts and resulting from heavy braking are significantly associated with an increased risk of heart attacks.

Researchers in Germany looked at the relationship between road traffic air pollution, composed of nitric oxide and particulates, and heart attack occurrence.

The formation of nitric oxide (NO) is stimulated by high-temperature combustion, particularly from diesel engines.

Besides being emitted during combustion, particulates can also be produced from the abrasion of brakes and tyres, as well as from dust.

Higher daily levels of NO were found to correlate with a higher incidence of heart attacks in 18,000 Berliners.

Experts said that smokers seemed unaffected by the smog because they already inhale toxic fumes.

Air pollution may be responsible for up to 11,000 deaths from heart disease and circulatory conditions in the UK annually.

“The correlation between air pollution and heart attacks in our study was absent in smokers.

“This may indicate that bad air can actually cause heart attacks since smokers, who are continuously self-intoxicating with air pollutants, seem less affected by additional external pollutants,” said Dr Insa de Buhr-Stockburger, from the Berlin Brandenburg Myocardial Infarction Registry.

“The study indicates that dirty air is a risk factor for acute myocardial infarction [heart attacks] and more efforts are needed to lower pollution from traffic and combustion.

“Causation cannot be established by an observational study.

“It is plausible that air pollution is a contributing cause of myocardial infarction, given that nitric oxide and PM10 promote inflammation, atherosclerosis is partly caused by inflammatory processes, and no associations were found in smokers.”

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